On the Use of Ultrasonic Absorption for the Determination of Very Rapid Reaction Rates at Equilibrium: Application to the Liquid Phase Association of Carboxylic Acids

1953 ◽  
Vol 21 (10) ◽  
pp. 1784-1790 ◽  
Author(s):  
Eli Freedman
Keyword(s):  
Liquid Phase ◽  
Carboxylic Acids ◽  
Reaction Rates ◽  
Ultrasonic Absorption ◽  
Rapid Reaction

scholarly journals A Relaxation Method for the Determination of Moderately Rapid Reaction Rates near Chemical Equilibrium.

1958 ◽  
Vol 12 ◽  
pp. 1834-1850 ◽  
Author(s):  
Stig Ljunggren ◽  
Ole Lamm ◽  
Inga Marie Nilsson ◽  
Jaakko Pispa
Keyword(s):  
Chemical Equilibrium ◽  
Relaxation Method ◽  
Reaction Rates ◽  
Rapid Reaction

Multi-walled Carbon Nanotubes Reinforced into Hollow Fiber by Chitosan Sol-gel for Solid/Liquid Phase Microextraction of NSAIDs from Urine Prior to HPLC-DAD Analysis

2019 ◽  
Vol 20 (5) ◽  
pp. 390-400 ◽  
Author(s):  
Nabil N. AL-Hashimi ◽  
Amjad H. El-Sheikh ◽  
Rania F. Qawariq ◽  
Majed H. Shtaiwi ◽  
Rowan AlEjielat
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Phase ◽  
Hollow Fiber ◽  
Sol Gel ◽  
Liquid Phase Microextraction ◽  
Extraction Device ◽  
Multi Walled Carbon Nanotubes ◽  
Solid Liquid ◽  
Walled Carbon Nanotubes

Background: The efficient analytical method for the analysis of nonsteroidal antiinflammatory drugs (NSAIDs) in a biological fluid is important for determining the toxicological aspects of such long-term used therapies. Methods: In the present work, multi-walled carbon nanotubes reinforced into a hollow fiber by chitosan sol-gel assisted-solid/ liquid phase microextraction (MWCNTs-HF-CA-SPME) method followed by the high-performance liquid chromatography-diode array detection (HPLC–DAD) was developed for the determination of three NSAIDs, ketoprofen, diclofenac, and ibuprofen in human urine samples. MWCNTs with various dimensions were characterized by various analytical techniques. The extraction device was prepared by immobilizing the MWCNTs in the pores of 2.5 cm microtube via chitosan sol-gel assisted technology while the lumen of the microtube was filled with few microliters of 1-octanol with two ends sealed. The extraction device was operated by direct immersion in the sample solution. Results: The main factors influencing the extraction efficiency of the selected NSAIDs have been examined. The method showed good linearity R2 ≥ 0.997 with RSDs from 1.1 to 12.3%. The limits of detection (LODs) were 2.633, 2.035 and 2.386 µg L-1, for ketoprofen, diclofenac, and ibuprofen, respectively. The developed method demonstrated a satisfactory result for the determination of selected drugs in patient urine samples and comparable results against reference methods. Conclusion: The method is simple, sensitive and can be considered as an alternative for clinical laboratory analysis of selected drugs.

The Use of Piezosensors for Determination of Carboxylic Acids in the Intermediate Products of Edible Ethanol Production

2020 ◽  
Vol 56 (14) ◽  
pp. 1379-1383
Author(s):  
Cao Nhat Linh ◽  
O. V. Duvanova ◽  
S. Yu. Nikitina ◽  
A. N. Zyablov
Keyword(s):  
Ethanol Production ◽  
Carboxylic Acids ◽  
Intermediate Products

Kinetics of esterification of monoisopropylphenols with phosphoryl trichloride

1989 ◽  
Vol 54 (5) ◽  
pp. 1311-1317
Author(s):  
Miroslav Magura ◽  
Ján Vojtko ◽  
Ján Ilavský
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Reaction Rates ◽  
Activation Energies ◽  
The Individual ◽  
Kinetics Of

The kinetics of liquid-phase isothermal esterification of POCl3 with 2-isopropylphenol and 4-isopropylphenol have been studied within the temperature intervals of 110 to 130 and 90 to 110 °C, respectively. The rate constants and activation energies of the individual steps of this three-step reaction have been calculated from the values measured. The reaction rates of the two isomers markedly differ: at 110 °C 4-isopropylphenol reacts faster by the factors of about 7 and 20 for k1 and k3, respectively. This finding can be utilized in preparation of mixed triaryl phosphates, since the alkylation mixture after reaction of phenol with propene contains an excess of 2-isopropylphenol over 4-isopropylphenol.

scholarly journals Expert System for Catalytic Titrimetry—Part 2: Determination of Monobasic Carboxylic Acids

1998 ◽  
Vol 81 (5) ◽  
pp. 1077-1086
Author(s):  
Biljana F Abramovic ◽  
Borislav K Abramovic ◽  
Ferenc F Gaál ◽  
Danilo M Obradovtc
Keyword(s):  
Expert System ◽  
Carboxylic Acids ◽  
Selective Determination

Abstract An expert system (ES) to solve the problem of choosing a catalytic titrimetric procedure for determining monobasic carboxylic acids is described. Carboxylic acids were divided into 3 groups—aliphatic, aromatic, and α-aminocarboxylic acids— based on their behavior in catalytic titrations with different indicator reactions, titrant, and/or solvent and the possibility of their selective determination in the presence of other acids

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